Hydrocatalytic refining of lubricating oils



United States Patent 3,245,003 HYDROCATALYTHC REFINHNG F LUBRIC-ATING OILS 7 Claims. in. 208-264) This invention relates to the hydrocatalytic refining of lubricating oils.

It is known to replace the conventional acid and clay treatments used as the final treatments in the production of lubricating oils, that may have been previously subject to dewaxing and/ or solvent extraction, by a mild hydrocatalytic treatment, and a particularly effective process of this kind uses a catalyst comprising the oxides or iron and molybdenum, and, if desired, of cobalt, supported on alumina. In order to obtain products having a maxi mum color stability, it is necessary to activate the catalyst by treatment at a temperature somewhat higher than that required for the refining treatment itself. This can usually be done by passing the oil to be refined in admixture with hydrogen over the catalyst at'said higher temperature for a period of approximately 48 hours.

However, it may happen that a particular oil to be refined is not itself suitable for carrying out the activation treatment and it is therefore desirable to have available a method of activating the catalyst that is independent of the oil to be refined. The present invention provides such a method.

According to the invention, a catalyst for the hydrocatalytic refining of lubricating oils and comprising the oxides of iron and molybdenum and, if desired, of cobalt, supported on alumina, is activated by contacting the catalyst at a temperature of at least 300 C. and in the presence of hydrogen with from 80 to 120 kg. of carbon disulfide per metric ton of catalyst.

Preferably, the carbon disulfide is brought into contact with the catalyst in a carrier oil which does not itself activate the catalyst. An oil of low sulfur content is preferred, for example, one with not more than 0.1% wt. of sulfur.

The carrier oil need not be a lubricating oil, but it is preferably a middle or heavy distillate petroleum fraction, i.e. one having an initial boiling point of at least 250 C. A convenient carrier oil is a lubricating oil which is incapable of activating the catalyst alone, for example a particular lubricating oil which is desired to refine after the activation. In this latter case no alteration of feed stock is required when activation ceases and refining commenoes;

As stated above it has been found that an amount of carbon disulfide of the order of 80-120 kg. per metric ton of catalyst is required to achieve satisfactory activation, the catalyst after activation having a sulfur content of the order of 10% wt. The activation may conveniently be carried out by adding at lea-st 0.1% Wt. of carbon disulfide to an oil which does not itself activate the catalyst and recycling the oil over the catalyst with addition of carbon disulfide to maintain the carbon disulfide content until the desired quantity of carbon disulfide has contacted the catalyst. The upper limit of carbon disulfide content may conveniently be not more than 10% wt., preferably not more than 5% wt.

The activation temperature should, as stated above, be at least 300 C. The upper limit may be determined by the undesirabil-ity of substantial carbon deposition on the catalyst during activation, and may conveniently be 400 'C. The length of the activation period will be determined 3,245,903 Ce Patented Apr. 12, 1966 by the rate at which carbon disulfide is passed over the catalyst, but it is preferably at least 24 hours. Other activation conditions are not so critical and can be varied within wide limits. Since the activation will normally be carried out in the same reactor as is used for the lubrieating oil treatment, suitable conditions may be chosen from the ranges suitable for the subsequent hydrocatalytic treatment.

The known catalysts which may be activated by the process of the present invention have the following preferred compositions:

Catalysts containing no cobalt oxide may have from 4 to 12% wt. of molybdenum oxide (M00 and 6 to 20% wt. of iron oxide (R2 0 the balance being alumina.

Catalysts containing three hydrogenatin g components may have from 3 to 20% wt. of molybdenum oxide (M00 1 to 12% wt. of cobalt oxide (C00) and 4 to 20% wt. of iron oxide (FeO the balance being alumina, and the ratio by weight of molybdenum oxide to cobalt oxide being at least 1.5:1.

Preferably the iron oxide content is from 1'0 to 20% wt., the molybdenum oxide content is from 10 to 20% wt. and the ratio by weight of molybdenum oxide to cobalt oxide is at least 3:1. The preferred composition of the catalyst by weight is as follows:

These catalysts may be prepared in known manner using, preferably, already calcined granular alumina. This pre-calcinat-ion may be carired out at normal calcination tempeartures of from 450 to 650 C., but higher temperatures in excess of 650 0, although not exceeding 900 C. are preferred to increase the pore diameter and total pore volume of the altunina. This has the effect of facilitating the subsequent impregnation, particularly that of the iron compound. The preferred alumina is one derived from an alumina trihydrate, particularly from hydrargillite.

The alumina should first of all be impregnated with a solution of ferric nitrate, and the acidification of this solution favors impregnation. This acidification is preferably effected by means of nitric acid up to the pH in the neighbourhood of 0. The impregnation should be effected by soaking the alumina in the ferric nitrate solution or by wetting the alumina with the solution or by any other equivalent method.

The impregnation of the alumina is followed by drying at C., then by calcination at 550 C.

The alumina, now impregnated with the oxide of iron, Fe 'O is then impregnated with 'a'solution of ammonium molybdate. The use of an ammoniacal solution of ammonium molybdate is necessary to facilitate impregnation of this salt and avoid its precipitation in contact with the alumina. One dries at 110 C. and calcines at 550 C. If it is desired to introduce cobalt into the catalyst, the impregnation with cobalt nitrate should be effected last, following the drying and calcination at 550 C. If desired, the calcin'ation between the impregnation with the ammonium molybdate and with the cobalt nitrate may be dispensed with but the catalyst then mns the risk of being less homogeneous and less active.

The hydrocatalytic refining of lubricating oils may be carried out using the activated catalyst at a temperature below the activating temperature within the range of to 340 C., preferably 250 to 320 C.

The pressure may vary between 5 ats. and 70 ats., but

EXAMPLE A catalyst having the following composition:

Percent Iron oxide, Fe O 12.9 Molybdenum oxide, M 9.9 Cobalt oxide, C00 2.8

Alumina 1 Balance was subjected to the following treatments.

(1) With a White oil having the following properties:

Density at C 0.880 Infiammability, AFFNOR, C. 232 Four point, C. 18

Acidity, mg./KOH/ g. 0.0040 De-emulsification, dry 30 Saybolt color +25 Total sulfur, percent by weight 0.15

Ramsbottom carbon, percent by weight 0.0020

Viscosity, Engler at 50 C. 5.48 Kinematic viscosity, centistokes At 100 F 74.08 At 122 F 41.1 At 210 F. 8.26 Viscosity index 85.7

Temperature C 350 Space velocity v./v./hour 1 Pressure kg./cm. Flow rate of hydrogen v./v./hour 20 Time hours .48

The catalysts so treated were used to refine the same Middle East spindle oil at the same space velocity, pressure and hydrogen rate but at various temperatures. The results are set out in the following table.

'ing temperature is from 250 to 320 C.

The stability is expressed by comparing the color of a sample before and after artificial aging for 16 hours at C. in the presence of" air. The ratio between the light absorption gives what one calls the index of reversion of the oil, an expression of its stability.

Index of reversion:

Absorption of the artificially aged oil Absorption of the fresh oil It will be seen that treatment of the white oil containing carbon disulfide was as effective for activation as the treatment with the Middle East spindle oil.

The invention also includes a catalyst that has been activated by the method of the invention and a process for the hydrocatalytic refining of lubricating oils using such a catalyst.

I claim:

1. A process for the mild hydrocatalytic refining o lubricating oils to improve their color and their oxidation and color stability properties without appreciable drop in viscosity which comprises first activating a catalyst by contacting same with from 80 to 120 kg. of carbon disulfide per metric ton of catalyst at a temperature of from 300 to 400 C. and in the presence of hydrogen, said catalyst containing from 4 to 20% wt. of iron oxide, 3 to 20% wt. of molybdenum oxide, 1 to 12% wt. of cobalt oxide, and the balance alumina, said oxides being supported on said alumina and the ratio by weight of molybdenum oxide to cobalt oxide being at least 1511, and thereafter contacting the lubricating oil feedstock in the presence of hydrogen and at a temperature below the activity temperature of said catalyst and within the range 150-350 C. with the activated catalyst to hydrocatalytically refine same.

2. A process as claimed in claim 1 wherein the catalyst has a ratio by weight of molybdenum oxide to cobalt oxide of at least 3:1, an iron content of 14 to 15% wt., a molybdenum oxide content of 10 to 11% wt., and a cobalt oxide content of 3.3 to 3.7% wt.

3. A process as claimed in claim 1 wherein the refin- 4. A process as claimed in claim 1 wherein the activation and the refining are carried out at a pressure of from 5 to 70 atmospheres, a hydrogen rate of from 5 to 150 volumes/volume of oil, and an oil feed rate of from 0.5 to 6.0 vol./vol. of catalyst/hour. I p

5. A process for the mild hydrocatalytic refining of lubricating oils to improve their color and their oxidation and color stability properties without appreciable drop in viscosity which comprises first activating a catalyst by contacting same with a carrier oil having no activation Table 1 Catalyst activated with- Hydrogenation Properties of the hydrogenated temperature oil White oil White 011 20 NS plus 3% CS2 Kuwait 225 C Reversion index 1. 59 1. 12 1. 27

ASTM color before reversion 1. 7 2. 4 1. 3 ASTM color after reversion 2. 1' 2. 65 1. 45 Increase in color density 0. 41 0. 17 0. 250 C Reversion index 1. 74 l. 09 1. 30

ASTM color before reversion- -1. 5 1. 95 1. 2 ASTM color after reversiornj 1. 9 2. 1 1. 35 Increase in color density 0.375 0.0855 0. 090 275 C Reversion index 1. 32 1. 11 1. 42 ASTM color before reversion 1. 5 v 1. 7 1. 15 AS'IM color after reversi0n 1. 7 g 1. 8 1. 3 Increase in color density 0.165 0.077 0. 300 O Reversion index 1.37 V 1.13 1.95 ASTM color before reversionv 1. 45 1. 7. 1. 25 ASTM color after reversion 1. 65 r 1. 85 p '1. 6 Increase in color density 0. 17 0. 091 0. 325

The index of reversion referred to herein is determined as follows.

The color of the oil is measured as expressed ,by light absorption using a photocolorimeter Bonet-Maur'y through a Wratten screen No. 7.

properties toward thecatalyst and having a carbon disulfide present therein in an amount of 0.1 to 10% wt., the amount of carbon disulfide being contacted with the catalyst being from 80 to kg. of carbon disulfide per metric ,ton of catalyst at a temperature of from 300 to 400 C.

and in the presence of hydrogen, said catalyst containing from 4 to 20% wt. of iron oxide, 3 to 20% wt. of molybdenum oxide, 1 to 12% wt. of cobalt oxide, and the balance alumina, said oxides being supported on said alumina and the ratio by weight of molybdenum oxide to cobalt oxide being at least 1.521, and thereafter contacting the lubricating oil feedstock in the presence of hydrogen and at a temperature below the activating temperature of said catalyst and within the range 150340 C. with the activated catalyst to hydrocatalyticaliy refine same.

6. A process as claimed in claim 5 wherein the carrier oil has a sulfur content of not more than 0.1% Wt.

7. A process as claimed in claim 5 wherein the carrier oil is recycled over the catalyst with the addition of carbon 6 disulfide until the desired quantity of carbon disulfide has contacted the catalyst.

References Cited by the Examiner UNITED STATES PATENTS 2,998,377 8/1961 Beuther et a1. 208264 3,012,963 12/1961 Archibald 208264 3,020,228 2/ 1962 Demeester 208--216 3,072,564 1/1963 Stewart et al 208-264 3,078,221 2/ 1963 Beuther et a1. 208264 DELBERT E. GANTZ, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner. 

1. A PROCESS FOR THE MILD HYDROCATALYTIC REFINING OF LUBRICATING OILS TO IMPROVE THEIR COLOR AND THEIR OXIDATION AND COLOR STABILITY PROPERTIES WITHOUT APPRECIABLE DROP IN VISCOSITY WHICH COMPRISES FIRST ACTIVATING A CATALYST BY CONTACTING SAME WITH FROM 80 TO 120 KG. OF CARBON DISULFIDE PER METRIC TON OF CATALYST AT A TEMPERATURE OF FROM 300* TO 400*C. AND IN THE PRESENCE OF HYDROGEN, SAID CATALYST CONTAINING FROM 4 TO 20% WT. OF IRON OXIDE, 3 TO 20% WT. OF MOLYBDENUM OXIDE, 1 TO 12% WT. OF COBALT OXIDE, AND THE BALANCE ALUMINA, SAID OXIDES BEING SUPPORTED ON SAID ALUMINA AND THE RATIO BY WEIGHT OF MOLYBDENUM OXIDE TO COBALT OXIDE BEING AT LEAST 1.5:1, AND THEREAFTER CONTACTING THE LUBRICATING OIL FEEDSTOCK IN THE PRESENCE OF HYDROGEN AND AT A TEMPERATURE BELOW THE ACTIVITY TEMPERATURE OF SAID CATALYST AND WITHIN THE RANGE 150*-350*C. WITH THE ACTIVATED CATALYST TO HYDROCATALYTICALLY REFINE SAME. 